The present invention relates to traction distributing devices for motor vehicles, which enable active control of the rate of distribution of traction with regard to right- and left-wheel shafts.
One of the known traction distribution devices is shown in the bulletin xe2x80x9cDirect Yaw Control Systemxe2x80x9d published by HONDA MOTOR, CO., LTD. on May 29, 1996.
FIG. 4 shows a drive system including such a traction distribution device. A transmission 100 includes a differential-gear mechanism 101 which serves to equally distribute traction to shafts 103, 102 of right and left wheels 106, 105. A unit 104 is mounted to the left-wheel shaft 102 to ensure active control of the rate of distribution of traction with regard to the wheel shafts 103, 102. Disposed coaxially in the unit 104 are a right sun gear 107 mounted to the right-wheel shaft 103, a central sun gear 108 mounted to the left-wheel shaft 102, a left sun gear 110 mounted to a sun-gear shaft 109, and a carrier 114 for rotatably supporting pinions 111, 112, 113 integrated therewith. The pinions 111, 112, 113 are engaged with the sun gears 107, 108, 110, respectively, to be capable of revolving on their axis and therearound. A right-cornering clutch 117 is interposed between the carrier 114 and a casing 115 of the unit 104, whereas a left-cornering clutch 116 is interposed between the sun-gear shaft 109 and the casing 115.
When the vehicle comers right, the right-cornering clutch 117 fixes the carrier 114 so that a transmission system including the sun gear 107, the pinions 111, 112, and the sun gear 108 increases the rotating speed of the left-wheel shaft 102 with respect to that of the right-wheel shaft 103. It is understood that active control of the rate of distribution of traction with regard to the right- and left-wheel shafts 103, 102 contributes to an improvement in the cornering performance, etc. of the vehicle.
With the known traction distribution device, however, active control of the rate of distribution of traction with regard to the right- and left-wheel shafts 103, 102 is ensured by switching of complicated gear trains, resulting in inevitable increase in size, weight, and manufacturing cost of the device.
It is, therefore, an object of the present invention to provide traction distribution devices for motor vehicles which contribute to a reduction in size, weight, and manufacturing cost.
One aspect of the present invention lies in providing a traction distribution device for a motor vehicle with a differential-gear mechanism for transmitting torque of a differential casing to wheel shafts, the device comprising:
a source of a hydraulic pressure, the source including a hydraulic pump which produces the hydraulic pressure by torque of the differential casing;
a hydraulic motor arranged in the differential-gear mechanism, the motor providing relative torque between one of the wheel shafts and the differential casing in accordance with a direction of the hydraulic pressure supplied thereto;
means for controlling the hydraulic pressure supplied to the motor; and
means for switching the direction of the hydraulic pressure supplied to the motor.
Another aspect of the present invention lies in providing a traction distribution device for a motor vehicle with a differential-gear mechanism for transmitting torque of a differential casing to wheel shafts, the device comprising:
a hydraulic pump arranged to produce a hydraulic pressure by torque of the differential casing;
a hydraulic motor arranged in the differential-gear mechanism, the motor providing relative torque between one of the wheel shafts and the differential casing in accordance with a direction of the hydraulic pressure supplied thereto;
a first valve interposed between the source and the motor, the first valve controlling the hydraulic pressure supplied to the motor; and
a second valve interposed between the source and the motor, the second valve switching the direction of the hydraulic pressure supplied to the motor.